This invention relates to reading and recording digital information, and more particularly, to disc drive devices.
Disc drives that read and record digital information on a disc-shaped information storage medium are in wide-spread use. Such discs include compact discs (CDS), read-only-memory compact discs (CD-ROMs), rigid magnetic discs, and flexible magnetic discs. Rigid magnetic discs include both fixed discs and removable discs that are housed in cartridges. An example of a removable cartridge having a rigid disc assembly is the JAZ(trademark) cartridge and an example of a removable cartridge having a flexible magnetic disc assembly is a ZIP(trademark) cartridge, both of which are produced by the assignee of the present invention, Iomega Corporation, Roy, Utah.
FIG. 4 (prior art) illustrates a conventional rigid disc assembly 110a that includes hub assembly 112 and platter 114a. Hub assembly 112 includes a metallic hub 116a, a clamp 118, and multiple rivets 120. Platter 114a is held between surfaces of the clamp 118 and hub 116, which are held together by rivets 120. Unfortunately, rivets 120 may cause distortion of platter 114a because of dimensional imperfection or dis-uniformity in producing or assembling the components. Even if the components are produced with tight manufacturing and assembly tolerances, platter distortion may still be a problem because of the sensitivity of the reading and recording process to even small amounts of distortion. Specifically, distortion of platter 114a as small as an order of magnitude of 1.0xc3x9710xe2x88x926 inch may cause interruption of the reading and recording process. The industry trend toward increasing areal density of stored information will likely diminish the acceptable amount of distortion.
Furthermore, platter 114a may slip with respect to hub 116a upon shock to disc assembly 110. Such slip may cause the center of platter 114 to be misaligned with the center of spindle motor 122a, which leads to difficulty in track following by the heads. Although removable cartridges are naturally more prone to shocks that may cause such slip, fixed discs (not shown) may also be subject to such shock, especially during shipping and installation. Moreover, the tight tolerances and several steps required to produce hub assembly 112 result in high cost of discs. Users of information storage discs are sensitive to cost and the industry is cost competitive.
FIG. 5 (prior art) illustrates another conventional disc assembly 110b that includes a platter 114b and a hub 116b. Platter 114b is affixed to a mating surface 117 of hub 116b by an adhesive. Not only does using adhesive have the disadvantages of platter 110a discussed above, but using adhesives causes additional difficulty in the assembly process. For example, adhesives can out-gas and deposit back onto the discs in the drive and cause head stiction and flying height problems. Also imprecise or dis-uniform application of the adhesive may weaken the joint and the adhesive may inadvertently be spilled or splattered onto the information-bearing surface, which may interrupt reading and recording information, and may also damage the heads. The disadvantages of disc assemblies 110a and 110b described herein apply to both rigid and flexible discs, and to fixed and replaceable discs.
It is desirable to provide a disc assembly, and associated disc drive, that diminishes slipping of the platter if subject to shock, that holds the platter uniformly around its inner circumference to eliminate localized distortion near clamp rivets, and that is less costly and more easily produced without extraordinarily tight tolerances of the components.
Data storage disc assemblies that, among other attributes, are simple to produce, that eliminate or diminish slippage when subjected to shock, that eliminate distortion from fasteners, and that are produced without adhesives are provided. The embodiments of the disc assemblies of the present invention include a clamp having a contact portion and a protruding member, a hub having a receptacle and a center hollow, and a platter having a center aperture. The receptacle receives the protruding portion to affix the clamp to the hub through the center aperture of the platter. Although the platter contains magnetic media, or alternatively optical media, for recording information, the hub and clamp contact portion contact the platter in an area that lacks information storage. The clamp has a feature that enables it to be affixed to the hub without mechanical fasteners and without adhesives, as well as self-aligning features. Furthermore, because the hub and clamp hold the platter substantially uniformly around the perimeter of the center aperture, angular distortion is minimized.
In a first embodiment, a stake on the underside of a clamp is inserted into a void in a hub. The clamp is forced against the hub, depressing a center portion of the clamp, until the stake protrudes through the void. The stake is heated to flatten its head, thereby forming a rivet-like structure that affixes the clamp to the hub. A bevel portion of the clamp aligns the platter with respect to the clamp. This self-aligning feature forces the centers of the clamp, hub, and platter into alignment. Therefore, the platter is joined to the hub, and eventually to a spindle motor, by a simple method that has few steps, and that forms a simple device that has few parts.
Similarly, a second embodiment of the present invention includes a self-aligning bevel feature. A clamp of this embodiment is pressed into an annular channel formed in a hub to form a press fit. In a third embodiment, the clamp is similarly inserted into a hub channel in a press fit. However, rather than a bevel surface, the third embodiment has a flat, horizontal surface to axially contact the platter surface and a flat, vertical surface to radially hold a rim face of the platter""s center aperture.
The present invention encompasses methods for forming the disc assemblies described herein without using fasteners or adhesives. Further, the present invention encompasses a disc drive comprising a spindle motor for cooperating with the disc assembly, a transducer for reading and recording digital information on the disc, and an actuator for positioning the transducer. Such a disc drive may include the disc assembly according to the present invention as an integral part of the drive, or the disc drive may be capable of receiving the disc assembly as a part of a removable cartridge.
The disc assemblies and methods according to the present invention securely join the hub, clamp, and platter together without mechanical fasteners and without adhesives. As used in this specification and in the appended claims, the term xe2x80x9cmechanical fastenersxe2x80x9d broadly includes rivets, pins, screws, bolts and the like; and the term xe2x80x9cadhesivexe2x80x9d includes any conventional or novel adhesive, flux, glue, grease, sealant and any other substance that possesses adhesive properties.